Rolls comprising a single web such as for example, long paper, a film, or a metal foil, or a composite sheet such as, for example, a laminated film having been wound upon a hollow core are widely used in various fields of industrial applications. For example, in an offset rotary press or a typographical rotary press, a web feeding device having loaded thereon a printing paper web (hereinafter referred to as "web") which is wound into the form of a roll (hereinafter referred to as "web roll") so as to deliver the web therefrom to a web consuming mechanism is indispensable.
As the web feeding device, a mill roll stand of the so-called turret system type in which two arms, supported upon a pivotal shaft so as to extend in substantially opposite directions, are integrally turned, as shown in FIG. 5, is conventionally used. This mill roll stand designated by means of the numeral 10 in the attached drawings has two pairs of arm mechanisms, each comprising an upper arm and a lower arm wherein both are shown with the same reference numeral of 14, which are connected to a pivotal shaft 12 by means of splines, not shown as shown in FIG. 5, wherein only one arm mechanism is illustrated, and wherein further the upper arm 14 and the lower arm 14 are disposed in such a way that they may be extended from the pivotal shaft 12 so as to have a reversed L-shape. This pivotal shaft 12 is driven by means of a motor (not shown) to turn the upper arm 14 and the lower arm 14 integrally together within a predetermined angular range. Incidentally, the pair of arm mechanisms are moved closer together or farther apart relative to each other by driving another motor (not shown) in the positive or negative direction.
At the tip of each arm 14, a conical or pyramidal center block 16 is supported so as to oppose the tip of the corresponding arm 14 of the other arm mechanism, the center block 16 being freely rotatable. This center block 16 is designed to have dimensions such that its tip can be inserted into a paper tube 20 which serves as the core of the web roll 18. Incidentally, a brake means (not shown) actuatable by means of a solenoid or an air pump for preventing overrun of the web which may be caused by the inertia generated by means of the rotation of the web roll 18 is coaxially disposed with respect to each center block 16 so as to exert a suitable amount of braking force with respect to the rotation of the center block 16.
As illustrated, at a position interposed between the upper arm 14 and the lower arm 14, there is disposed a conventional splicer 22 which performs the splicing of the webs.
In the mill roll stand 10 having the aforenoted construction, the web delivered from the web roll 18 loaded within the pair of arms 14 extending upwardly is fed to a rotary press (not shown) disposed downstream of the splicer 22, as shown in FIG. 5, wherein the center blocks 16 rotate freely upon the arms 14 as the web roll 18 rotates and unwinds. When the tension of the web changes as the web is consumed and the diameter of the web roll 18 is reduced, the braking means exerts a suitable amount of braking force with respect to the rotation of the center blocks 16.
Next, when the web roll being fed is replaced by means of another web roll 18 of a different type in accordance with an order change during the operation of the line, a braking force is applied to the center blocks 16 so as to stop the rotation of the web roll 18. Then, as shown in FIG. 6, the splicer 22 performs an automatic splicing operation between the web roll which has been delivering a web (hereinafter referred to as "used web") and the web of a web roll 18 which is disposed in a stand-by posture (hereinafter referred to as "new web") loaded within the lower pair of arms 14, and after cutting of the used web, the splicer 22 performs successive feeding of the new web to the web consuming device of the rotary press.
Immediately after this splicing operation, the splicer 22 is shifted toward the right a predetermined distance so as to avoid interference with the used web roll 18 loaded within the upper pair of arms 14 as the splicer 22 operatively assists in performance of the subsequent web-feeding operation, as shown in FIG. 7. The pivotal shaft 12 is then turned counterclockwise through a predetermined angle so as to dispose the used web roll 18 at a position for transfer onto a web roll transportation means (not shown) such as a flat car, and then the unloaded center blocks 16 mount another web roll therebetween.
On the other hand, a mill roll stand of the so-called swing arm type which is widely known and has a construction which is different from that of the turret system, and other mill roll stands of special construction such as, for example, a drive system or the like are also used. In the chain drive system mill roll stand, a pair of endless routes are provided in parallel with respect to each other and with a predetermined space defined therebetween, and an endless chain is extended along each of the routes such that it can freely travel therealong. A plurality of bases are disposed upon the endless chains with predetermined spaces defined therebetween, and center blocks are disposed upon each base pair such that they may approach each other. More particularly, within the mill roll stand of such a system, a plurality of web rolls are rotatably mounted between a plurality of center blocks disposed within the mill roll stand, and splicing between the used web roll and a new web roll is performed within a known splicer disposed above the mill roll stand.
However, the mill roll stands of the systems mentioned above are all designed such that, when the diameter of the web roll 18 rotatably mounted between the center blocks 16 is reduced after consumption of the web or when a used web roll is to be replaced with another web roll of a different type in accordance with an order change, splicing between the web and old or used the web of a new web roll 18 may be performed within the splicer 22.
In the illustrated mill roll stand 10 of the turret system type, the cut end portion of the used web, after completion of the splicing and cutting operations within the splicer 22, hangs undesirably from the web roll 18, as is clear from FIGS. 6 and 7. More particularly when a web roll 18 loaded within the upper pair of arms 14 is to be replaced, the cut end portion of the web hanging from the web roll 18 is disposed within the vicinity of the splicer 22 and may possibly therefore interfere with or to damage the new web being fed or alternatively, cause damage to or a malfunction within the splicer 22, which is, of course, operationally undesirable.
Therefore, prior to the web roll replacement, a trouble-some operation of rewinding the hanging web onto the body of the used web roll is required by means of an operator, making the automation of the roll replacement difficult or time-consuming. This rewinding operation is also some-what dangerous, since the operator must step into the mill roll stand. Moreover, it can be pointed out that if the web roll has a sufficiently large diameter and hence has a considerable amount of weight, the operator is endangered still further because he is liable to encounter the roll which has great inertia generated as a result of the rewinding operation of the used web roll.
Not only in the mill roll stand of the turret system type but also in those of the swing arm system type and of the chain drive system similar problems likewise exist.
Under such circumstances, the present applicant has proposed an invention entitled "WEB FEEDING DEVICE" and has accordingly filed a patent application on Apr. 15, 1988. The "web feeding device" according to this prior invention can be evaluated highly in that the center blocks are rotated in the direction which is opposite to that of the web delivering direction by a suitable drive means, whereby the web hanging from the web roll after completion of the splicing and cutting procedures can automatically be rewound onto the body of the web roll. However, the web may again be inadvertently delivered out from the web roll during the processes of loading, unloading and replacement of the webs, since the rewound cut end portion of the web is not fixed to the body of the web roll.
Therefore, an operator must in fact apply adhesive tape to the cut end portion of the web so as to fix it onto the body of the web roll after rewinding the web and moving the web roll to a web replacing position. Consequently, it is seen that if a device according to the prior invention is used, it still requires manual operations to be performed in connection with the replacement of the rolls, and thus full automation of the roll replacing procedures has been difficult to attain.